1. Field of the Invention
The present invention relates to an optical transceiver, in particular, the invention relates to a mechanism to conduct heat from a transmitter optical subassembly (hereafter denoted as TOSA) to a metal housing.
2. Related Background Arts
An optical transceiver ordinarily includes a TOSA, a receiver optical subassembly (hereafter denoted as ROSA), an electrical circuit communicating with the TOSA, the ROSA and the host system, and a housing for enclosing the TOSA, the ROSA, and a circuit board mounting the electronic circuit. The TOSA installs a semiconductor laser diode (hereafter denoted as LD) therein. The LD is often necessary to be operated under a constant temperature; so, the TOSA installs a thermo-electric cooler (hereafter denoted as TEC). The TEC generates large heat to cool the temperature of the LD. Accordingly, the TOSA with the TEC is required to dissipate heat generated by the TEC.
FIG. 10 shows a conventional arrangement of the TOSA 101 in the housing, 102 and 103. The TOSA has a rectangular package or a co-axial CAN package, where the heat generated in the package may be radiated from the side surfaces of the package. Moreover, the side surfaces of the TOSA 101 extend substantially in parallel to the longitudinal axis of the housing. Accordingly, putting a material, 106a or 106b, with good thermal conductivity such as a thermal sheet, a thermal gel and the like between the side surface of the package 101a and the housing, 102 or 103, an effective heat conducting path may be established from the TOSA 101 to the housing. However, the conventional arrangement described above is limited in a case where the heat radiating surface of the TOSA 101 faces and is substantially in parallel with the inner surface of the housing. Recent TOSA does not always provide such a heat radiating surface.
In particular, when the TOSA provides a ceramic package whose side surfaces are made of multi-layered ceramics and the heat radiating surface thereof is limited to the bottom portion of the package and the bottom extends in directions perpendicular to the longitudinal axis of the housing; another arrangement to establish a path to conduct heat from the package of the TOSA to the housing is necessary.